Fixed Oils and Essentials Oils in Oral Hygiene – a Brief Outlook

ABSTRACT

The present work underlines the importance of employing fixed and essential oils in oral care. Fixed oils such as coconut oil, sesame oil and essential oils such as oil of clove, cinnamon, tea tree, peppermint etc. are useful in preventing oral infections, reducing plaque formation and soothing oral mucosa. The diverse phytoconstituents of these oils contribute to the efficacy of oral care formulation. As part of the study, in addition to the literature review on oils related to oral hygiene, the composition of various marketed oily mouthwashes was noted to know about the oils employed. The reported oral care applications of various fixed oils and essential oils have been comprehensively summarized and presented. Secondly, antibacterial activity against Streptococcus mutans was studied for selected fixed oils, essential oils and a marketed product “Perfora”. From the study, it was observed that various fixed oils can be used as vehicles with the blend of essential oils. Antibacterial activity suggested that the zone of inhibition (in mm) of the essential oils was comparable to the standard compound (tetracycline) and the antibacterial activity of the fixed oils was similar to that of the marketed product. This study highlights the application of fixed and essential oils in oral health care and research.

Keywords: Fixed Oils, Essential Oils, Oil Pulling, Oral Hygiene, Dental Care

1. INTRODUCTION

Oral health is an inseparable part of general health. A variety of disorders affect oral health, thus making oral diseases one of the most critical areas of concern. Although they are preventable, the negligence towards oral health leads to pain, discomfort and can become a bane. The conditions affecting the oral cavity include caries, tooth ache, tooth decay, bad breath, gum inflammation, mucosal disturbance, oral ulcers and sores etc.

Dental caries, periodontal diseases and oral cancers are key areas of national oral health concern. Till date, there have been only two national health surveys conducted in India. The first national level epidemiological oral health survey in India was conducted by Dental Council of India in 2004. The next survey was done in 2007. An attempt was made to assess the state-wise global disease burden (GDB) of India in 2016.^1,2 The Global Oral Health Status Report, WHO (2022) estimated that oral diseases affect close to 3.5 billion people.³ Globally, about 2 billion people suffer from caries of permanent teeth. 514 million children are estimated to suffer from caries of primary teeth.² The Indian dental care market was valued at USD 0.65 billion in 2022 and can reach USD 1.34 billion by 2030. One of the major contributing factors to the growth of Indian dental care market is the rising knowledge and awareness among individuals regarding various dental aids that aim to improve personal oral health and hygiene.⁴

The oral hygiene armamentarium consists of toothpaste, tooth brush, dental floss, mouthwash, gargle, mouth fresheners and tongue cleaner. These products are used once or twice in a day for maintenance of healthy teeth and gums. These are well established methods for maintenance of oral health but certain drawbacks are associated with these interventions. Toothpaste and toothbrush are effective only when used properly and regularly. Toddlers and children need to be specially monitored when they brush. Many a times, children use more amount of toothpaste than the suggested pea size and tend to swallow it due to its appealing taste. In India, the percentage of dentists and people who use dental floss is quite less as patience and skill is required to use the floss.⁵ Mouthwashes are popular products for dental care. Although, the mouthwash maintains the oral health, it also comes along with several drawbacks such as aggravation of halitosis, burning sensation, xerostomia and taste disturbance. Research studies have shown that mouthwashes can be potential oral cancer initiators. Treatment for oral health conditions is expensive and usually not part of universal health coverage (UHC).^6,7

2. OIL PULLING

Oil pulling is an ancient Ayurvedic technique, described in the textbook “Charaka Samhita”. It is mentioned under the names “Gandoosha” and “Kavalagraha”. In Gandoosha, a mouthful of medicated oil is taken and held for a specific period of time until lacrimation and nasal discharge occurs and then the oil is spitted out. In Kavalagraha, an individual’s mouth is filled upto three-fourth with the medicated oil and swished for some time. When the oily solution turns white, foamy and tasteless, it is then spitted out. Oil pulling may be beneficial in reducing the number of bacteria in the mouth, improving gum health and preventing issues like bad breath and cavities. It is also used to prevent xerostomia, gum inflammation and periodontitis..^7-9 It is a simple technique that can be added to one’s routine conveniently.

3. OILY VEHICLE BASED MOUTHRINSES – AN OVERVIEW

Oily vehicle-based mouthrinse is an emerging prophylactic and a therapeutic product for oral hygiene. It is a monophasic liquid dosage for external use only. The formulation contains either a single oily ingredient or combinations of various fixed oils and essential oils. Incorporation of herbal extracts, fatty acids or triglyceride molecules can improve the pharmaceutical and therapeutic properties of the formulation. It does not need any dilution with water unlike regular aqueous mouthwashes.¹⁰ A randomized clinical study was conducted to determine the efficacy of the individual fixed oils, as oily mouthrinses, in comparison to the conventional aqueous mouthwashes.¹¹ Coconut oil and sesame oil are the most commonly used oil pulling agents. The mechanism of cleansing action and efficacy of oil pulling as a therapy, in adherence to the Ayurvedic principles, was confirmed. Thus, the notion of placebo effect of the oil pulling is refuted.¹² Essential oils cannot be used as oil pulling agents independently due to the high concentration of active principles and extremely strong organoleptic properties. Recent trends highlight the importance of essential oils as crucial components in increasing the performance of aqueous mouthwashes. Thus, essential oils form an integral part in improving the performance of oil pulling. Several studies have shown the application of essential oils in oral care due to their biodiverse activities.¹² The oils were effective in controlling the oral disorders as manifested by the change in oral indices.

3.1 Commercially available oily vehicle-based products

Based on an online search as well as by visiting community pharmacies, some marketed oily mouthwashes were identified. Their composition was noted and is presented in Table 1.

Table 1: List of some of the marketed oily vehicle-based mouthwashes and their composition

3.2 Reported work on oils for oral hygiene

Coconut oil is the most commonly used vehicle in oil pulling. It confers better palatability and therapeutic property to oily mouthwash and decreases the oral pathogenic count.^24,25 It is absorbed through the oral mucosa and helps in removal of toxins present in oral cavity. It can be used as an adjunct to treat gingivitis and plaque.²⁶ It also acts as an efficient sialogogue.²⁷ The major drawback of the coconut oil is its freezing point (23-240C). Solidification of coconut oil is characterized by development of solid particles, haziness or turbidity, at or below the temperature of 240C. It is due to high proportion (about 50%) of lauric acid.²⁸ Monolaurin, a monoglyceride derived from lauric acid, is responsible for the antimicrobial action against oral pathogens.²⁹

Sesame oil contains high amount of unsaturated fatty acids such as oleic acid and linoleic acid. Presence of Vitamin E and lignans such as sesamin, sesamol and sesamolin are responsible for stabilizing the oil against oxidative degradation.³⁰ The freezing of point of sesame oil is -60C, thus it decreases the freezing point of the formulation, when blended with coconut oil.³¹ It is an excellent agent to prevent dental caries.³² Studies have shown that gentle application of sesame oil can be beneficial in managing the oral care routine and prevention of associated diseases in geriatric patients.³³ Ozonated sesame oil was found to significantly reduce the Streptococcus mutans count.³²

Other fixed oils such as flaxseed oil, pumpkin seed oil and chiaseed oil can be explored as excipients in treating oral disorders. Flaxseed oil is found to have good anti- inflammatory property and acts as an anti-gingival agent.³⁴ It is useful in wound healing associated with periodontitis.³⁵ It is found to have cytotoxic effect on cell lines associated with oral cancer.³⁶ It decreases the oxidative stress on oral tissues due to its antioxidant property.³⁷ Pumpkin seed oil is found to have significant role in treating mouth ulcer.³⁸ It is associated with lowering of the risk of oral cancer due to its antioxidant property.³⁹ Chiaseed oil is rich in ω-3-fatty acids and antioxidants; thus, useful in oral wound healing and has a soothening effect on oral mucosa.⁴⁰

Essential oils can show antimicrobial, anti-inflammatory, antioxidant properties and confer better organoleptic properties to oral care products. Thus, essential oils can show synergistic action with fixed oils to treat oral disorders.²⁹ The antibacterial activity of individual essential oils in Table 2 is comparable to that of synthetic medicaments.

The most commonly used essential oils in oral care dosage forms include clove oil, cinnamon oil, peppermint oil, eucalyptus oil and tea tree oil. Eugenol and cinnamaldehyde present in clove oil and cinnamon oil respectively are the phytochemicals importance for oral care. Phytoconstituents such as eucalyptol, thymol and menthol are utilized by the combination of essential oils of eucalyptus, thyme and peppermint oil in aqueous mouthwashes such as LISTERINE®.⁴¹ These essential oils can be incorporated to provide relief from periodontitis.⁴² They are effective in alleviating plaque and gingivitis.¹³ Cinnamon oil is found to inhibit the growth of oral pathogens such as S. mutans and P. gingivalis .⁴³ Clove oil can be used as a dental anaesthetic as well as an antiseptic.¹⁶ Eucalyptus oil containing dental care formulations is used to strengthen gums and prevent gum bleeding.⁴⁴ Peppermint oil is the most common flavorant in oral care dosage forms. It produces numbing effect on the gums and relieves gum ache.⁴⁵ It is used to treat halitosis as it is a good sialogogue.⁴⁶ Terpinen-4-ol in tea tree oil produces antimicrobial action against oral pathogens. Tea tree oil is widely used as an anti-plaque and anti-gingivitis agent and can potentiate the activity of the fixed oils.⁴⁷ Lemon oil and orange oil are incorporated for their flavoring property. Their ability to prevent the release of volatile sulphur compounds in oral environment is an effective remedy to treat halitosis.⁴⁸

Hempseed oil and vanilla oil are used in Habbits natural mouthwash for treating teeth sensitivity.⁴⁹ Lavender oil, rosemary oil, myrrh oil, chamomile oil, bergamot oil, ylang-ylang oil and lemongrass oil are some of the essential oils which are less commonly used to treat oral concerns. Efforts have shown that the dilution of 1 to 2 drops of these essential oils with water can be used as prophylactic oral care intervention.⁵⁰

4. ANTIBACTERIAL ACTIVITY STUDY OF SELECTED OILS

Based upon the literature review and survey of marketed formulations conducted, few fixed oils and essential oils were identified and procured. These oils were evaluated for their antibacterial activity by determination of zone of inhibition using well diffusion method. Streptococcus mutans, a common oral pathogen, was used as the test organism.⁵¹ S. mutans cell suspension was prepared and grown on media and incubated for 24 hrs at 37°C. The cell suspensions of the cultures were adjusted to 1-2 X106 cells/ ml. The medium was then inoculated with bacteria and incubated in aerobic chamber. Tetracycline (25µl) was used as the standard compound. The oil samples and one of the marketed products, “Perfora”, (25 µl each) was added into the wells in the agar plates. The treated plates were incubated in aerobic chamber at 37°C for 24hrs and then observed for zones of inhibition around the wells. The inhibitory activity of the procured oils and marketed formulations are characterised in Table 2 and shown in Figure 1.

Table 2: Inhibitory activity of test compounds against test organism

S-Standard (Tetracycline), 1- Flaxseed oil,2- Perfora, 3-Coconut oil, 4- Sesame oil,

5- Peppermint oil, 6- Clove oil,7- Chiaseed oil, 8- Pumpkin seed oil, 9- Cinnamon oil

5. CONCLUSION

Incorporation of fixed and essential oils into oral hygiene practices offers a promising addition to conventional oral care methods. Their traditional use in practices such as oil pulling, combined with contemporary research supporting their efficacy, underscores their potential as effective oral care agents. Although, the efficacy of fixed oils was limited in comparison to the synthetic oral care agents, these oils could be used as oral health interventions. Oily mouthwashes could be used as an alternative to conventional mouthwashes and safer adjuvant to toothbrushing. With certain paediatric population oils rinses may find use once safety and efficacy are established. The oily rinses would aid in overcoming some drawbacks of conventional aqueous mouthwashes. Continued research and clinical validation are essential to fully harness their therapeutic potential and ensure safe and effective use within modern dental care frameworks.

Acknowledgments: The authors thank the higher authorities and the management for their support.